Using Layer Modifiers for a More Accurate DWG Export in Revit

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On average, Revit does a good job of isolating disciplines and their settings. That said, have you ever had to export your Mechanical file to DWG?  

I recently had a request from one of my Civil Engineers – if Systems can be placed on separate layers/levels (water, sewer, fire protection, storm drain, elec, comms) for exports. On average, Revit does a good job of isolating disciplines and their settings. That said, have you ever had to export your Mechanical file to DWG?  Then tried turning off just the Supply Duct or Sanitary Pipe layer in the exported file. You can’t because All duct/Pipe are exported to the same layers (P-PIPE or M-HVAC-DUCT).

When exporting, Revit does not distinguish between the different Duct and Pipe systems. It exports based on elements Category. I have found this largely effects Duct, Pipe and Equipment in the Mechanical models the most.  I do see it occasionally in my Architecture and Interiors models. When both are in the same model, I want the Interiors layers to start with “I” and the Architectural layers to start with an “A”.  Layer Modifiers can help with this.

From the File tab: Go down to the Export option. Select CAD Formats. Select DWG from the list

In the Export window Select the “ … “ button

On the bottom left of the window, select the New Export Setup option. Name the new Export Setup

Select the Collapse All option. This will make it easier to navigate the categories in the list.

Expand the Modifiers category. The categories under Modifiers can be expanded and customized as needed. They can then be used in the Add/Edit Modifiers options to customize the layer a model category exports to.

From here forward, propel will have different approaches and preferences to how they work. I will be showing my preferred settings, you can follow these or develop your own based on your needs.

I start with the Worksets… Expand the Worksets category to see a list of the Worksets in your model. Set the Layer column to the discipline designator associated with the Workset. For Example: Mech-Ductwork would be M Plumb-Sanitary would be P Etc… In my template I have Worksets for the different discipline links also. I set them all to XREF

The Workset modifiers will be used to set the discipline designator of the export layer.

Other options I select and edit are the System Type, Phase Status & the 3 Custom options. Below are examples of the naming I used for each option.

• System Type will be used to define the System designator of the layer
• Phase Status will be sued to define the Phase Status of the layer
• Custom options will be used for things that have no category.
  • I use them for the Center Line and Rise/Drop options of Pipe and Duct

Once the Modifiers have been set, scroll up to the Model Categories option.

Lets start with the Duct categories.

• Under the Layer column,
  • Name the category with a basic designator for what it is. For all “Duct” categories, I use HVAC.
• Select a category and pick the Add/Edit… button in the Layer Modifiers column.

Selecting the Add/Edit… button will open the Layer Modifiers window. In the Available Modifiers window is a list the Modifier categories that can be used to construct the layer for the selected category. Add the categories from that list to the Modifiers Added window using the left/right arrows between the windows. The highlighted modifier, in the category’s column, will reflect the text that was edited in the Layer column in the Model Categories.

In this example we selected Duct Accessories.

• The {workset} will report M
• The {Phase Status} will report the phase of the element
• The {Duct Accessory} category will report HVAC.
• The {System Type} will report the assigned System

The resulting layer made in the DWG for Duct Accessories will be something like this:

• New Supply Duct Accessory, the layer would read M-HVAC-SUPP
• Demo Supply Duct Accessory, the layer would read MD-HVAC-SUPP
• Existing Supply Duct Accessory, the layer would read ME-HVAC-SUPP

Repeat these steps for each category that needs to export to a specific system. Modify them as needed to use the available modifiers that have been assigned. Not all categories need Modifiers, some work fine the way they are.

With an out of the box export all that would be exported would be M-HVAC-DUCT and M-PIPE. With the layer modifiers you get a more accurate representation of the elements in the model. For the few elements that do not export properly return to the export list and edit the modifier options to export them accurately.